KO: Circulatory System
Subject: Science | Year: 6
Name: _________________________ Class/Set: ____________ Date: ____________
1. Key Knowledge / Core Facts
- Double Circulatory System: Humans have two loops; one pumps blood to the lungs, the other pumps blood to the rest of the body.
- The Heart: A powerful muscular organ that acts as a pump to circulate blood continuously.
- Four Chambers: The heart is divided into four sections: the right atrium, right ventricle, left atrium, and left ventricle.
- Oxygenated Blood: Blood rich in oxygen (bright red), which travels from the lungs to the heart and then to the body.
- Deoxygenated Blood: Blood that has given up its oxygen (darker red), returning from the body to the heart to be sent to the lungs.
- Lungs: The organ where gas exchange occurs; blood picks up oxygen and releases carbon dioxide.
- Diffusion: The process where oxygen and nutrients move from the blood into the body's cells.
2. Key Vocabulary
- Aorta: The largest artery in the body; it carries oxygenated blood away from the heart.
- Vena Cava: The main vein that brings deoxygenated blood back into the right side of the heart.
- Pulmonary: A term relating specifically to the lungs (e.g., the pulmonary artery carries blood to the lungs).
- Valves: Tiny flaps in the heart and veins that act like one-way doors to prevent blood flowing backwards.
- Nutrients: Essential substances, such as glucose, carried in the blood to provide energy for cells.
- Excretion: The process of the blood carrying waste products (like carbon dioxide) to organs that remove them.
3. Blood Vessels
- Arteries: Robust vessels with thick, elastic walls that carry blood away from the heart under high pressure.
- Veins: Thinner-walled vessels that carry blood towards the heart; they contain valves to help blood flow against gravity.
- Capillaries: Microscopic, thin-walled vessels that form a vast network to allow oxygen and nutrients to reach every cell.
- Pulse: The rhythmic expansion and contraction of an artery as the heart pumps blood through it.
- Vascular System: The collective name for the network of all arteries, veins, and capillaries in the body.
4. Components of Blood
- Red Blood Cells: Disk-shaped cells containing haemoglobin; their primary job is to transport oxygen.
- White Blood Cells: The body's "soldiers"; they identify and destroy pathogens like bacteria and viruses.
- Platelets: Small cell fragments that clump together to clot blood and form scabs when the skin is cut.
- Plasma: The straw-coloured liquid part of the blood that carries cells, nutrients, and waste products.
- Haemoglobin: A protein in red blood cells that bonds with oxygen to carry it around the body.
5. Health and Lifestyle
- Exercise: Physical activity strengthens the heart muscle and improves the efficiency of the circulatory system.
- Heart Rate: The speed at which the heart beats, measured in beats per minute (BPM); it increases during exercise.
- Balanced Diet: Eating low-fat foods prevents the build-up of fatty deposits in the arteries.
- Drugs: Substances like tobacco and alcohol can damage heart tissue and cause blood vessels to narrow.
- Obesity: Carrying excess weight puts additional strain on the heart and increases the risk of heart disease.
- Recovery Rate: The time it takes for the heart rate to return to normal after exercise; a faster recovery indicates better fitness.
6. Working Scientifically (Pulse Rates)
- Independent Variable: The factor you choose to change in an experiment, such as the type or intensity of exercise.
- Dependent Variable: The factor you measure to see the effect, such as the pulse rate in BPM.
- Control Variables: Factors kept the same to ensure a fair test, such as the duration of exercise or the person being tested.
- Prediction: A scientific statement describing what you expect to happen based on existing knowledge.
- Data Accuracy: Taking measurements carefully (e.g., using a stopwatch) and repeating tests to find an average.
⚠ TEACHER’S GUIDANCE
💡 Pedagogical Insights
- Model: Use a "Circuit" analogy. The heart is the battery, the blood vessels are the wires, and the blood cells are the delivery vans.
- Explain: Address the common misconception that deoxygenated blood is blue. Clarify that it is actually dark red, and only appears blue through the skin due to light reflection.
- Scaffold: For lower-ability students, provide a diagram of the heart alongside this Knowledge Organiser to help them visualise the four chambers and major vessels.
- Extend: Challenge Greater Depth (GDS) students to explain why the left ventricle has thicker muscular walls than the right ventricle (it must pump blood to the whole body, not just the lungs).
🔬 Safety & Nuance Check
- Sensitivities: Be mindful when discussing heart health or pulse rates, as some students may have underlying medical conditions or family histories of heart disease.
- Practical Safety: When measuring pulse rates during exercise, ensure students have adequate space and are wearing appropriate footwear to prevent trips or falls.